Thin-Film Device Eyed as Power Source for Wearable Tech

With wearable electronics becoming a trend, researchers are exploring a number of new ways to provide small and flexible power sources to accommodate them. Rice University has approached the problem by using nickel-based electrodes to develop a flexible supercapacitor that acts much like a battery without the need for lithium, James Tour, a Rice chemist who is leading the research, tells Design News in an email.

Researchers chose to create a supercapacitor rather than a battery because it can perform in a similar way but is less complex to develop, he told us. The power source also provides flexibility, not just in structure, but also in performance. It can both charge and discharge more quickly than a battery -- as supercapacitors generally do -- or be developed to charge more slowly and thus put out prolonged output in a way similar to that of a battery, Tour says.

A thin-film energy storage device, seen attached to a polymer backing, retains its battery-like and supercapacitor-like qualities even after being flexed 1,000 times, according to tests at Rice University. Rice chemist James Tour led the team that developed the supercapacitor, which can be used to power wearable electronics and flexible devices. (Source: Jeff Fitlow/Rice University)

"Batteries need two different electrodes in the structure, which makes them more complex to build, whereas supercapacitors usually have two pieces of identical electrodes, and they do not need lithium metal shuttling back and forth," he says.

The end result is an electrochemical capacitor about a hundredth of an inch thick, but which can scale up by increasing its size or by adding layers to it, according to researchers. In tests, a device the size of a square inch held 76% of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles.

It seems to me one potential benefit of super capacitors would be to quickly capture power from a charging system and then free the device to be moved away while the super capacitor trickle charges the battery at whatever rate is best for the battery.

The advantage of a super capacitor over a battery is that it can charge relatively faster as compared to a battery; but the disadvantage is that the super cap discharges also pretty quickly; Also, what about the leakage? Unless these specs are improved, I can't see how the super caps could possibly replace batteries in near future...for mobile phones. Where as the super caps could be ideal for many wearable electronics application where size matters.